Aspects of embodiments concerns an apparatus for tuning a drum, the drum comprising a drum shell having an upper skin, the apparatus comprising: an outer static rim that is removably operably coupleable to the inside wall of a drum shell; a diameter adjustment mechanism that is removably operably coupleable with the drum shell, the diameter adjustment mechanism including one or more inner cylindrical shells mountable within the drum shell and being configured for axial displacement whereby an upper rim thereof can be selectively brought into or out of contact with an upper skin of the drum and thereby change an effective diameter of the upper skin.